I'm always amazed at the level of escalation in Japanese media depictions of "Bullying".
In the West it was classically dunking someone's head in a toilet or stuffing them into a locker.
In Japan it's scribbling death threats across their desk, beating them until half-dead, killing their pets, MURDERING THEIR FAMILY AND RAPING THEM. AT 12 YEARS OLD.
On another note the FMC continues to be dumber than the wheelbarrow of bricks and it's rather jarring how infatuated she's become with our MC seemingly out-of-nowhere despite their few interactions 'til now and his explicit threat of killing her if she meddles in his revenge, but that's probably because the passage of time in-universe is mostly mentioned in narration so there may be more background that's happening off-screen.